Evaluation of the upper lip bite test in predicting difficult laryngoscopy

Abstract Study Objective To evaluate the accuracy of the upper lip bite test (ULBT) in predicting difficult laryngoscopy. Design Prospective, observational outcome study. Setting Operating room of a large tertiary-care academic medical center. Patients 6,882 consecutive adult, ASA physical status I, II, III, IV, and V patients, scheduled for procedures in all surgical specialties. Interventions Upper lip bite test class was determined for all patients preoperatively. Measurements The Cormack & Lehane grade of laryngeal view was determined at endotracheal intubation. Main Results Only 171 patients had ULBT class III, predicting a difficult laryngoscopy, while 173 patients presented with a Cormack & Lehane grade of 3 or 4. Of the 173, 14 patients had a previous ULBT class of III. Sensitivity and positive predictive value of the ULBT were 8.1% and 8.2%, respectively. Conclusions The ULBT is a poor predictor of difficult laryngoscopy when used as the single bedside screening test in a North American patient population. Its use cannot be recommended.